This invention relates generally to phthalocyanine compounds, and more particularly to the preparation of aryloxy, arylthio, alkyloxy, and alkylthio phthalocyanine compounds and their subsequent incorporation into semiconducting thin films by the Langmuir-Blodgett technique.
Phthalocyanine, or tetrabenzetraazaporphyrin, compounds are crystalline molecular substances characterized by intense color, high thermal oxidative stability, and extreme insolubility. They display properties such as electrical conductivity, electrical switching between conductive states, photovoltaic effects, oxidative catalytic activity, and electrochromism. The electrical properties of these compounds can change in response to the presense of chemical vapors, electromagnetic radiation, and electrical potential.
However, these compounds must typically be formed into thin layers before they can be used in micro electronic devices. To the extent that these layers are not of optimal thickness or are otherwise imperfect or disorderly, the usefulness of phthalocyanine-based electronic devices is degraded. Prior art attempts at phthalocyanine film formation worked around the problem of the low solubility of phthalocyanine by using evaporative or mechanical film formation techniques. The present invention takes a different approach: it discloses how phthalocyanine can be modified to become soluble, while retaining desirable electrical properties. The modification is accomplish without modifying the carbon skeleton of phtalocyanine. Such modification involves complicated chemistry and greatly increases manufacturing expense.